One embodiment relates to a modular wiring system having locking elements. The wiring system comprises a wiring unit or module and a functional unit or functional module. The wiring unit can be for coupling to the ends of wires such as a phase wire, a neutral wire and a ground wire. The functional module can be for example in the form of a receptacle or a light switch. Other types of modular units are known in the art, for example, U.S. Pat. No. 7,052,313 to Gorman, which issued on May 30, 2006, the disclosure of which is hereby incorporated herein by reference in its entirety.